1. Field of the Invention
The present invention relates to image processing apparatuses and methods, and recording media and programs used therewith. In particular, the present invention relates to an image processing apparatus and method that increase accuracy of motion vector detection, and to a recording medium and program used therewith.
2. Description of the Related Art
In an image processing apparatus for converting the frame frequency of an image, the gradient method described in Japanese Unexamined Patent Application Publication No. 60-158786 is used as a method for detecting a motion vector in a block of interest. Although the gradient method has a feature capable of detecting a movement below pixel size by performing a simplified arithmetic operation, the method has bad accuracy for detection in units of pixels. Accordingly, in an ordinary case, it is common that motion vector detection is performed by accumulating detected values in units of blocks.
Therefore, conventionally, the gradient operation is performed by using a pixel of interest, which is subject to motion vector detection, or all pixels in an operation block set in the vicinity of a block of interest. Ideally, when pixels in the operation block have substantially equivalent movements, a probable motion vector is detected.
However, pixels in an object having a movement different from that of the pixel of interest or the block of interest may come to be mixed into the operation block. In this case, it is common that improbable motion vectors are detected, thus causing a problem of significant deterioration in accuracy of motion vector detection. In addition, when the detected improbable motion vectors are used to perform frame frequency conversion, a resultant generated image has significant visual deterioration such as occurrence of noise or discontinuity in a boundary between objects in the image.